This name is a synonym of Sedum spathulifolium subsp. pruinosum (Britton) R.T. Clausen & C.H. Uhl.
The record derives from Tropicos
(data supplied on 2012-04-18)
which reports it as a synonym (record 8902047) with original publication details: Naturaliste Canad. 93(5): 646 1966.
Full publication details for this name can be found in IPNI: http://ipni.org/urn:lsid:ipni.org:names:231881-2.
This name was in version 1 of The Plant List, record tro-8902047.